Demand even if no message sink in JavaxWebSocketFrameHandler

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

jetty-websocket/websocket-javax-common/src/main/java/org/eclipse/jetty/websocket/javax/common/JavaxWebSocketFrameHandler.java

@@ -584,6 +584,7 @@ public class JavaxWebSocketFrameHandler implements FrameHandler
         if (activeMessageSink == null)
         {
             callback.succeeded();
+            coreSession.demand(1);
             return;
         }
 

jetty-websocket/websocket-javax-tests/src/test/java/org/eclipse/jetty/websocket/javax/tests/SingleMessageHandlerTest.java

@@ -0,0 +1,139 @@
+//
+// ========================================================================
+// Copyright (c) 1995-2021 Mort Bay Consulting Pty Ltd and others.
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License v. 2.0 which is available at
+// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+// ========================================================================
+//
+
+package org.eclipse.jetty.websocket.javax.tests;
+
+import java.net.URI;
+import java.nio.ByteBuffer;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+import javax.websocket.OnMessage;
+import javax.websocket.Session;
+import javax.websocket.server.ServerEndpoint;
+
+import org.eclipse.jetty.server.Server;
+import org.eclipse.jetty.server.ServerConnector;
+import org.eclipse.jetty.servlet.ServletContextHandler;
+import org.eclipse.jetty.util.BufferUtil;
+import org.eclipse.jetty.websocket.javax.client.internal.JavaxWebSocketClientContainer;
+import org.eclipse.jetty.websocket.javax.server.config.JavaxWebSocketServletContainerInitializer;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class SingleMessageHandlerTest
+{
+    private static final LinkedBlockingQueue<ByteBuffer> BINARY_MESSAGES = new LinkedBlockingQueue<>();
+    private static final LinkedBlockingQueue<String> TEXT_MESSAGES = new LinkedBlockingQueue<>();
+
+    private Server _server;
+    private ServerConnector _connector;
+    private JavaxWebSocketClientContainer _client;
+
+    @BeforeEach
+    public void before() throws Exception
+    {
+        _server = new Server();
+        _connector = new ServerConnector(_server);
+        _server.addConnector(_connector);
+
+        ServletContextHandler contextHandler = new ServletContextHandler();
+        JavaxWebSocketServletContainerInitializer.configure(contextHandler, ((servletContext, serverContainer) ->
+        {
+            serverContainer.addEndpoint(TextEndpoint.class);
+            serverContainer.addEndpoint(BinaryEndpoint.class);
+        }));
+        _server.setHandler(contextHandler);
+
+        _server.start();
+        _client = new JavaxWebSocketClientContainer();
+        _client.start();
+    }
+
+    @ServerEndpoint("/binary")
+    public static class BinaryEndpoint
+    {
+        @OnMessage
+        public void onMessage(ByteBuffer message)
+        {
+            BINARY_MESSAGES.add(message);
+        }
+    }
+
+    @ServerEndpoint("/text")
+    public static class TextEndpoint
+    {
+        @OnMessage
+        public void onMessage(String message)
+        {
+            TEXT_MESSAGES.add(message);
+        }
+    }
+
+    @AfterEach
+    public void after() throws Exception
+    {
+        _client.stop();
+        _server.stop();
+    }
+
+    @Test
+    public void testBinary() throws Exception
+    {
+        URI uri = URI.create("ws://localhost:" + _connector.getLocalPort() + "/binary");
+        EventSocket eventSocket = new EventSocket();
+        Session session = _client.connectToServer(eventSocket, uri);
+
+        // Can send/receive binary message successfully.
+        ByteBuffer binaryMessage = BufferUtil.toBuffer("hello world");
+        session.getBasicRemote().sendBinary(binaryMessage);
+        assertThat(BINARY_MESSAGES.poll(5, TimeUnit.SECONDS), is(binaryMessage));
+
+        // Text message is discarded by implementation.
+        session.getBasicRemote().sendText("hello world");
+
+        // Next binary message is still received.
+        session.getBasicRemote().sendBinary(binaryMessage);
+        assertThat(BINARY_MESSAGES.poll(5, TimeUnit.SECONDS), is(binaryMessage));
+
+        session.close();
+        assertTrue(eventSocket.closeLatch.await(5, TimeUnit.SECONDS));
+    }
+
+    @Test
+    public void testText() throws Exception
+    {
+        URI uri = URI.create("ws://localhost:" + _connector.getLocalPort() + "/text");
+        EventSocket eventSocket = new EventSocket();
+        Session session = _client.connectToServer(eventSocket, uri);
+
+        // Can send/receive text message successfully.
+        String textMessage = "hello world";
+        session.getBasicRemote().sendText(textMessage);
+        assertThat(TEXT_MESSAGES.poll(5, TimeUnit.SECONDS), is(textMessage));
+
+        // Binary message is discarded by implementation.
+        session.getBasicRemote().sendBinary(BufferUtil.toBuffer("hello world"));
+
+        // Next text message is still received.
+        session.getBasicRemote().sendText(textMessage);
+        assertThat(TEXT_MESSAGES.poll(5, TimeUnit.SECONDS), is(textMessage));
+
+        session.close();
+        assertTrue(eventSocket.closeLatch.await(5, TimeUnit.SECONDS));
+    }
+}